Reprograms the Toyota A340 and Jeep AW4 valve body for short, firm shifts that cut clutch slip in hot rods, 4x4s and work trucks.
Whether it sits behind a 22R-E or 3VZ in a 4Runner or Pickup, a V8 in a Lexus or Tundra, or the 4.0L in a Jeep Cherokee, the Aisin four-speed family wears out clutches the same way: long, soft shifts that turn friction material into heat. The TransGo 340-HD2 Reprogramming Kit is the one kit TransGo builds for all of them, the Toyota A340, A341 and A343 and the Jeep AW4. It is new, made in the USA and ships from the USA. Pick it if you tow, run bigger tires, have added power, or are rebuilding and want the new clutches to last.
These units choose gears electronically, but apply feel is set by the hydraulics: the primary regulator and cut back valves set line pressure against throttle, and accumulators soften each clutch and brake apply. The 340-HD2 recalibrates those pieces with new regulator and cut back springs, new accumulator springs with short, medium and long spacers, and drill bits for opening chosen separator plate feed holes. The supplied valves include a hardened lock-up relay boost valve and bushing for the soft original, plus an optional low-hold setup so the transmission stays in first with the lever in manual low. TransGo describes the result as short, firm shifts for street, strip and off-road use.
A shift kit will not fix a dead shift solenoid, a bad speed sensor or clutches already worn out. Rule those out first with the solenoid resistance test.
Do a hydraulic test with the fluid hot, reading line pressure in Drive and Reverse at idle and at stall, as Toyota's factory manual lays out. Low pressure in every range points to the TV cable adjustment, regulator valve or pump; low in only one range points to a leak in that circuit. Healthy pressure with soft shifts is where this kit helps most. Our pressure testing guide covers the gauge setup, and the Aisin slipping guide helps separate a calibration complaint from a worn unit.
The kit fits the Toyota A340, A341 and A343 and the Jeep AW4. TransGo's product page says 1985-on; its printed instructions say 1987-2007, so very early units are worth checking against your valve body before ordering. The instructions cover four valve body types told apart by the solenoid layout and whether the relief valve sits at the front or the rear, and bolt lengths and check ball spots vary between them. The lock-up relay boost valve does not suit some Lexus valve bodies. Valve body gaskets are not in the box, and TransGo counts 17 variations, so buy gaskets matched to your exact model; TransGo also sells a 340-VB-G set that covers them all. Send us your year, model and VIN if you are unsure. More parts are in the Aisin collection.
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Yes. The AW4 in the Cherokee and Comanche shares the Aisin A340-family valve body design, and TransGo lists the A340, A341, A343 and AW4 under the same 340-HD2 kit.
No. TransGo says there are 17 gasket variations and you need the ones that match your exact model. They offer a 340-VB-G set covering all of them.
Yes. TransGo states it installs with the transmission in the vehicle, though a helper makes lining up the manual valve easier.
That depends on the feed hole sizes you drill. Truck sizes give firm but civil shifts; the larger hot rod sizes are noticeably harder.
The kit covers the A341 used in Lexus models, but TransGo notes the lock-up relay boost valve does not suit some Lexus valve bodies. Check your valve body type before installing that piece.
It is optional and keeps the transmission in first gear when the lever is in manual low, instead of upshifting on its own. Useful for steep descents and off-road driving.
